1. Field of the Invention
The present invention relates to an image correction apparatus and an image correction method for performing correction processing on a target image to generate a corrected image. Furthermore, the present invention relates to an electronics device such as an imaging device including the aforementioned image correction apparatus.
2. Description of Related Art
A camera shake correction technique is a technique that reduces the amount of camera shake at the time of capturing an image, and is viewed as a major differentiation technique for imaging devices such as digital still cameras. Regardless of whether the correction target is a still image or moving image, such camera shake correction technique generally operates via separate individual procedures of detecting camera shake and a second technique for correcting an image on the basis of the detection result.
In the procedure for detecting camera shake, method stapes may include using a sensor such as an angular velocity sensor, an acceleration sensor or the like, and an electronic method of detecting camera shake by analyzing an image. In the image correction technique, method steps may include an optical camera shake correction technique for correcting an image by driving an optical system, and an electronic camera shake correction technique for correcting an image by image processing.
The camera shake correction technique for still images, comprises the methods of detecting camera shake by use of a sensor and then performing optical camera shake correction on the basis of the detection result, a method of detecting camera shake by use of a sensor and then performing electronic camera shake correction on the basis of the detection result, and a method of detecting camera shake by analyzing an image and then performing electronic camera shake correction on the basis of the detection result.
Among these stated methods, a description will be given of the method of detecting camera shake by use of a sensor, and then performing an electronic camera shake correction on the basis of the detection result. In this method, camera shake information is generated in advance by detecting camera shake during image capture. After capturing of the image, a corrected image is generated by reducing, on the basis of the camera shake information, the amount of shake of the image included in the captured image. The camera shake correction based on this procedure often is called an “image restoration type camera shake correction.” Various techniques have already been disclosed as techniques related to image restoration type camera shake correction in Japanese Patent Application No. Sho 62-127976 and Japanese Patent Application Laid-open Publications Nos. 2004-88567 and 2006-129236, for example.
Since no drive mechanism for an optical system is necessary, the image restoration type camera shake correction has the advantage of low cost, small size and low power consumption when compared with an optical type correction method. The image restoration type camera shake correction, however, has a demerit of taking longer time for correction. Although dependent of the image size of a correction target image, the correction can require approximately a few seconds, for example, when obtaining a single corrected image via reducing shake from a single correction target image.
A description will be given, with reference to FIG. 10, of the flow of events for generating a corrected image in an imaging device employing a desirable image restoration type camera shake correction. The exemplified imaging device is provided with a display unit and a correction button. In playback mode, a user first checks a captured image (original image) before correction, and thereafter, presses the correction button when necessary. After this button is pressed, the imaging device starts executing camera shake correction processing steps (image restoration processing) and displays a corrected image on a display screen upon completion of the camera shake correction processing.
In this method, the time required for obtaining a corrected image is quite long as mentioned above, so that the user has to wait until the corrected image can be displayed. This problem causes stress from wait time experienced by the user and degrades operability of the imaging device. Accordingly, there is an urgent need for development and improving timing technique.
In addition, Japanese Patent Application Laid-open Publication No. 2006-186764 discloses a technique for temporarily displaying an image obtained by performing camera shake correction on a reduced copy of the image, and performing camera shake correction on the actual captured image while the image based on reduced image is temporarily displayed. The purpose of this technique is to avoid the perception of the correction processing time. This technique, however, is related to the so-called additive-type image stabilization technique, which is quite different from the image restoration type camera shake correction technique. Accordingly, this technique is assumed to be used only in a case where correction is performed immediately after an image is captured. In the additive-type image stabilization technique, a plurality of divided exposure images are continuously captured by making the shutter speed faster. Substantially, a single still image is obtained by adding and synthesizing the plurality of divided exposure images to and with one another.